[Physiological and pathophysiological features of the control of lipolysis and lipid mobilization by natriuretic peptides]

We have demonstrated a potent and specific lipolytic effect of natriuretic peptides (NP) in human and primates' fat cells. The lipolytic effect of NP is mediated through intracellular production of cGMP and activation of the cGMP-dependent kinase 1alpha. Local infusion of atrial-NP (ANP), directly within the subcutaneous adipose tissue through a microdialysis catheter, increases lipolysis and stimulates blood flow through its vasodilating effect in lean healthy men. This effect is blunted in overweight men and can be recovered by endurance training. Intravenous infusion of physiological doses of ANP induces lipid mobilization. Higher concentrations of ANP that are encountered during heart failure also stimulate lipid oxidation. ANP activates lipolysis and free fatty acids release from adipose tissue during endurance exercise. This effect is paradoxically amplified when exercise is performed under beta-blockade treatment, because of an enhanced cardiac release of ANP. No gender differences in ANP-induced lipid mobilization during exercise have been found. Heart failure is associated with high circulating levels of NP that could participate to the progression toward cachexia. On contrary, a negative correlation between NP levels and body mass index is found in obese persons. The molecular basis of this inverse correlation is not yet demonstrated from a functional standpoint. Further studies are needed to clearly define the pathophysiological role of NP in obesity and heart failure.

Dynamic strength training improves insulin sensitivity without altering plasma levels and gene expression of adipokines in subcutaneous adipose tissue in obese men

CONTEXT

Obesity is characterized by a low-grade inflammatory state, which could play a role in insulin resistance. Dynamic strength training improves insulin sensitivity.

OBJECTIVE

The objective of this study was to investigate, in obese subjects, whether the insulin sensitizing effect of dynamic strength training is associated with changes in plasma levels and gene expression of adipokines potentially involved in the development of insulin resistance.

DESIGN

Twelve obese male subjects were investigated before and at the end of 3 months of dynamic strength training. Insulin sensitivity was evaluated using euglycemic-hyperinsulinemic clamp. Blood samples and needle biopsy samples of sc abdominal adipose tissue were obtained. The plasma levels and adipose tissue mRNA levels of adiponectin, leptin, IL-1beta, IL-6, and TNF-alpha were determined.

RESULTS

The training induced an increase in the whole-body glucose disposal rate by 24% (P = 0.04). The body weight was not altered during the training. Plasma levels of leptin decreased during the training (16.6 +/- 6.3 vs. 13.1 +/- 5.7 ng/ml) by 21% (P < 0.02), whereas no change in plasma levels of other adipokines and C-reactive protein was observed. Gene expression of the investigated adipokines was not changed in sc adipose tissue during the training.

CONCLUSIONS

In obese subjects, the dynamic strength training resulted in an improvement of whole-body insulin sensitivity. The increase in insulin sensitivity was not associated with training-induced modifications of plasma levels or adipose tissue gene expression of adipokines supposedly involved in the development of insulin resistance.

Cardiovascular and metabolic effects of natriuretic peptides

Natriuretic peptides (NP) are essential in mammals to regulate blood volume and pressure. The functional roles of NP are not limited to natriuresis and diuresis. Several peripheral and central actions of the peptides have been characterized. Studies on transgenic mice have revealed their key function in the regulation of cardiomyocyte growth. Plasma NP levels increase in patients with cardiovascular disorders and heart failure. They represent useful clinical markers for clinicians to diagnose heart diseases. The recent discovery of their potent lipolytic action in adipose tissue is a breakthrough in cardiovascular medicine. This new function of NP in the regulation of lipid metabolism offers interesting questions in the field of obesity, diabetes and cardiovascular diseases. This review will briefly describe the effects of NP on the cardiovascular system and lipid metabolism.

Atrial natriuretic peptide stimulates lipid mobilization during repeated bouts of endurance exercise

Atrial natriuretic peptide (ANP) controls lipolysis in human adipocytes. Lipid mobilization is increased during repeated bouts of exercise, but the underlying mechanisms involved in this process have not yet been delineated. The relative involvement of catecholamine- and ANP-dependent pathways in the control of lipid mobilization during repeated bouts of exercise was thus investigated in subcutaneous adipose tissue (SCAT) by microdialysis. The study was performed in healthy males. Subjects performed two 45-min exercise bouts (E1 and E2) at 50% of their maximal oxygen uptake separated by a 60-min rest period. Extracellular glycerol concentration (EGC), reflecting SCAT lipolysis, was measured in a control probe perfused with Ringer solution and in two other probes perfused with either Ringer plus phentolamine (alpha(1/2)-AR antagonist) or Ringer plus both phentolamine and propranolol (beta-AR antagonist). Plasma epinephrine, plasma glycerol, and EGC were 1.7-, 1.6-, and 1.2-fold higher in E2 than in E1, respectively. Phentolamine potentiated exercise-induced EGC increase during E2 only. Propranolol reduced the lipolytic rate during both E1 and E2 compared with the probe with phentolamine. Plasma ANP concentration increased more during E2 than during E1 and was correlated with the increase in EGC in the probe containing phentolamine plus propranolol. The results suggest that ANP is involved in the control of lipolysis during exercise and that it contributes to stimulation of lipolysis during repeated bouts of exercise.

The RIONI study rationale and design: validation of the first stored electrograms transmitted via home monitoring in patients with implantable defibrillators

Appropriate and inappropriate therapies of implantable cardioverter defibrillators (ICDs) have a major impact on morbidity and quality of life in ICD recipients. The recently introduced home monitoring of ICD devices is a promising new technique which remotely offers information about the status of the system. Stored intracardiac electrograms (IEGMs), which are essential for correct classification of appropriate and inappropriate ICD discharges, have until now not been available with ICD home monitoring on a day-by-day basis because of limitations of transferable data. We demonstrate the first compressed IEGMs daily transferable via home monitoring (IEGM-online). Validation of these electrograms will be performed in the Reliability of IEGM-Online Interpretation (RIONI) study. A total of 210 episodes of stored IEGMs will be collected by at least 12 European centres. The primary endpoint of this study is to investigate whether the IEGM-online based evaluation of the appropriateness of the ICDs therapeutic decision following episode detection is equivalent to the evaluation based on the complete ICD episode Holter extracted from the IEGM stored. The evaluation is independently done by an expert board of three experienced ICD investigators. The equivalence of the two methods is accepted if the evaluations yield a different conclusion for <10% of all evaluated IEGMs. The conclusion of the study is expected at the beginning of 2007. If RIONI successfully validates IEGMs transmitted via home monitoring, a strong basis for the use of this promising technique will be established.

[Natriuretic peptides: a new lipolytic pathway in human fat cells]

Human fat cell lipolysis was considered until recently to be an exclusive cAMP/protein-kinase A (PKA)-regulated metabolic pathway under the control of catecholamines and insulin. Moreover, exercise-induced lipid mobilization in humans was considered to mainly depend on catecholamine action and interplay between fat cell beta- and alpha2-adrenergic receptors controlling adenylyl cyclase activity and cAMP production. We have recently demonstrated that natriuretic peptides stimulate lipolysis and contribute to the regulation of lipid mobilization in humans. Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) stimulate lipolysis in human isolated fat cells. Activation of the adipocyte plasma membrane type A guanylyl cyclase receptor (NPR-A), increase in intracellular guanosine 3',5'-cyclic monophosphate (cyclic GMP) levels and activation of hormone-sensitive lipase mediate the action of ANP. ANP does not modulate cAMP production and PKA activity. Increment of cGMP induces the phosphorylation of hormone-sensitive lipase and perilipin A via the activation of a cGMP dependent protein kinase-I (cGK-I). Plasma concentrations of glycerol and nonesterified fatty acids are increased by i.v. infusion of ANP in humans. Physiological relevance of the ANP-dependent pathway was demonstrated in young subjects performing physical exercise. ANP plays a role in conjunction with catecholamines in the control of exercise-induced lipid mobilization. This pathway becomes of major importance when subjects are submitted to chronic treatment with a beta-blocker. Oral beta-adrenoceptor blockade suppresses the beta-adrenergic component of catecholamine action in fat cells and potentiates exercise-induced ANP release by the heart. These findings may have several implications whenever natriuretic peptide secretion is altered such as in subjects with left ventricular dysfunction, congestive heart failure and obesity.

Dynamic strength training improves insulin sensitivity and functional balance between adrenergic alpha 2A and beta pathways in subcutaneous adipose tissue of obese subjects

AIMS/HYPOTHESIS

The aim of this study was to investigate whether dynamic strength training modifies the control of lipolysis, with particular attention paid to the involvement of the antilipolytic adrenergic alpha 2A receptor (ADRA2A) pathway.

METHODS

Twelve obese men (age: 47.4+/-2.8 years; BMI: 32.7+/-0.9) were investigated during a 210-min euglycaemic-hyperinsulinaemic clamp conducted before and after 3 months of dynamic strength training. Before and during the third hour of the clamp, the lipolytic effect of a perfusion of isoproterenol or adrenaline (epinephrine) alone or associated with the ADRA2A antagonist phentolamine was evaluated using the microdialysis method of measuring extracellular glycerol concentration (EGC) in subcutaneous abdominal adipose tissue (SCAAT). In addition, biopsies of SCAAT were carried out before and after training to determine mRNA levels

RESULTS

The training increased insulin sensitivity in adipose tissue. The decrease of EGC was more pronounced during the clamp conducted after the training period than during the clamp done in pre-training conditions. Before and after the training, catecholamines induced an increase in EGC, the increase being lower during the clamp on each occasion. The isoproterenol-induced increase in EGC was higher after the training. Adrenaline-induced lipolysis was potentiated by phentolamine after but not before the training. There were no training-induced changes in mRNA levels of key genes of the lipolytic pathway in SCAAT.

CONCLUSIONS/INTERPRETATION

In obese subjects, dynamic strength training improves whole-body and adipose tissue insulin responsiveness. It increases responsiveness to the adrenergic beta receptor stimulation of lipolysis and to the antilipolytic action of catecholamines mediated by ADRA2As.

An Unsuspected Metabolic Role for Atrial Natriuretic Peptides

In normal and obese humans, lipid mobilization and systemic nonesterified fatty acid levels are thought to be acutely controlled by catecholamines (ie, epinephrine and norepinephrine) and insulin. Natriuretic peptides (NPs) are known to play a key role in the regulation of salt and water balance and blood pressure homeostasis. They are involved in the pathophysiology of hypertension and heart failure. NPs have recently been found to exert potent lipolytic effects (ie, activating the breakdown of stored triacylglycerols) in isolated human fat cells and to promote lipid mobilization in vivo. Atrial natriuretic peptide increases the intracellular 3', 5'-cyclic guanosine monophosphate (cGMP) concentration which activates cGMP-dependent protein kinase leading to perilipin and hormone-sensitive lipase phosphorylation and lipolysis. NPs promote lipid mobilization when administered intravenously. NPs are also responsible for the residual lipid-mobilizing action observed under oral beta-blockade in subjects performing physical exercise. NPs are therefore novel factors which may open promising research pathways to explain the control of lipid mobilization in physiological and pathological conditions. The metabolic impact of altered production and circulation of NPs remains to be established. The potential influence of NPs on the development of lipid disorders, obesity-related cardiovascular events, and cardiac cachexia will be discussed in this review.

Les peptides natriurétiques : Une nouvelle voie de régulation de la lipolyse chez l’homme

Human fat cell lipolysis was considered until recently to be an exclusive cAMP/protein-kinase A (PKA)-regulated metabolic pathway under the control of catecholamines and insulin. Moreover, exercise-induced lipid mobilization in humans was considered to mainly depend on catecholamine action and interplay between fat cell beta- and alpha2-adrenergic receptors controlling adenylyl cyclase activity and cAMP production. We have recently demonstrated that natriuretic peptides stimulate lipolysis and contribute to the regulation of lipid mobilization in humans. Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) stimulate lipolysis in human isolated fat cells. Activation of the adipocyte plasma membrane type A guanylyl cyclase receptor (NPR-A), increase in intracellular guanosine 3',5'-cyclic monophosphate (cyclic GMP) levels and activation of hormone-sensitive lipase mediate the action of ANP. ANP does not modulate cAMP production and PKA activity. Increment of cGMP induces the phosphorylation of hormone-sensitive lipase and perilipin A via the activation of a cGMP dependent protein kinase-I (cGK-I). Plasma concentrations of glycerol and non-esterified fatty acids are increased by i.v. infusion of ANP in humans. Physiological relevance of the ANP-dependent pathway was demonstrated in young subjects performing physical exercise. ANP plays a role in conjunction with catecholamines in the control of exercise-induced lipid mobilization. This pathway becomes of major importance when subjects are submitted to chronic treatment with a beta-blocker. Oral beta-adrenoceptor blockade suppresses the beta-adrenergic component of catecholamine action in fat cells and potentiates exercise-induced ANP release by the heart. These findings may have several implications whenever natriuretic peptide secretion is altered such as in subjects with left ventricular dysfunction, congestive heart failure and obesity.

Differential regulation of atrial natriuretic peptide- and adrenergic receptor-dependent lipolytic pathways in human adipose tissue

The aim of the study was to investigate the regulation affecting the recently described atrial natriuretic peptide (ANP)-dependent lipolytic pathway in comparison with the adrenergic lipolytic cascade. We studied in vivo the effect of a euglycemic-hyperinsulinemic clamp on the changes occurring in the extracellular glycerol concentration (EGC) of subcutaneous adipose tissue (SCAT) during ANP or epinephrine perfusion in a microdialysis probe. Homologous desensitization and the incidence of hyperinsulinemia on the ANP- and catecholaminergic-dependent control of lipolysis were also investigated in vitro on fat cells from SCAT. When perfused in SCAT, epinephrine and ANP promoted an increase in EGC; the EGC increase was significantly lower during the clamp. The reduction of epinephrine-induced lipolysis was limited (18%) when phentolamine (an alpha(2)-adrenergic receptor [AR] antagonist) was perfused together with epinephrine. Unlike the effect of epinephrine, the response to ANP observed during the second perfusion was reduced by 32%. The increase in extracellular guanosine 3',5' -cyclic monophosphate concentration, which reflects ANP activity, was also reduced during the second perfusion. Desensitization of the lipolytic effects of ANP was observed in vitro after a 2-hour period of recovery, while the effects of alpha(2)-AR agonist or of epinephrine were unchanged. Insulin was without any effect on ANP-induced lipolysis and alpha(2)-AR-mediated antilipolysis, while it reduced beta-AR-induced lipolysis. The ANP-dependent lipolytic pathway undergoes desensitization in vitro and in situ. Insulin had no inhibitory effect on either ANP- or alpha(2)-AR-dependent pathways, while it counteracted the beta-AR pathway.

Effect of endurance training on adrenergic control of lipolysis in adipose tissue of obese women

The effect of a 12-wk training program on sc abdominal adipose tissue (SCAAT) was studied in 11 obese women. Before and after the training, biopsies of SCAAT were performed for mRNA levels determination. Using the microdialysis method, involvement of alpha(2)- and beta-adrenergic receptor (ARs) in the control of lipolysis in SCAAT was studied using local perfusion of epinephrine alone or supplemented with phentolamine, an alpha(2)-AR antagonist. In addition, the variation in dialysate glycerol concentrations during exercise (50% peak oxygen consumption at 40 min) in a probe perfused with Ringer's solution was compared with that obtained in a probe perfused with Ringer's solution plus phentolamine. Training did not promote changes in the expression of key genes of the lipolytic pathway. The epinephrine-induced rise in the dialysate glycerol concentration was identical before and after training and was similarly potentiated by phentolamine. During exercise, the potentiating effect of phentolamine on the glycerol response was apparent before, but not after, training. The exercise-induced increase in plasma norepinephrine was lower after training (P = 0.04). In conclusion, training did not modify either the expression of genes involved in the control of lipolysis or alpha(2)- and beta-ARs in situ sensitivity to epinephrine in SCAAT. Training reduced the antilipolytic action of catecholamines mediated by alpha(2)-ARs during exercise, probably due to a reduction of exercise-induced catecholamine increase.

Aerobic training improves exercise-induced lipolysis in SCAT and lipid utilization in overweight men

The aim of this study was to investigate whether endurance training improves lipid mobilization and oxidation in overweight subjects. Eleven young men (25.6 +/- 1.4 yr and body mass index 27.7 +/- 0.2) performed a 4-mo training program consisting of practicing aerobic exercise 5 days/wk. Before and after the training period, lipid oxidation was explored during a 60-min exercise at 50% of peak O2 consumption by use of indirect calorimetry. Lipid mobilization and antilipolytic alpha2-adrenoceptor effect were also studied using the microdialysis method in abdominal subcutaneous adipose tissue (SCAT). After training, plasma nonesterified fatty acid (NEFA) levels, at rest and during exercise, were significantly lower than before (P < 0.001). Lipolysis in SCAT was significantly higher after than before training. An antilipolytic alpha2-adrenoceptor effect in SCAT was underlined during exercise before training and disappeared after. The respiratory exchange ratio was lower after training, i.e., the percentage of lipid oxidation was higher only at rest. The amount of lipid oxidized was higher after training, at rest, and during exercise. Although exercise power was higher after training, the relative intensity was equivalent, as suggested by a similar increase in plasma catecholamine concentrations before and after training. In conclusion, 4-mo training in overweight men improved lipid mobilization through a decrease of antilipolytic alpha2-adrenoceptor effect in SCAT and lipid oxidation during moderate exercise. Training induced a decrease of blood NEFA, predicting better prevention of obesity.

[Evaluation of the anatomopathological characteristics and the safety of radiofrequency lesions at the atrial level with two different systems of irrigated tip catheters on an experimental level]

INTRODUCTION AND OBJECTIVES

We performed this study to evaluate the security and efficacy in the lesions produced on the atrial wall by different irrigated catheters in an experimental model. We evaluated the anatomopathologic characteristics of the lesions produced by two different systems of irrigated tip catheters, with opened or closed circuit.

METHODS

This study was performed in 16 pigs applying 60 sec radiofrequency pulses with three different energy levels (15, 25 y 50 Watts). Two different systems of radiofrequency ablation irrigated catheters were used, opened and closed. We used 4 pigs in which we performed ablation with a standard catheter as a control group. Under fluoroscopic guidance, catheters were placed on the high and low right atrial lateral wall, where lesions were produced. After 7 days, animals were sacrificed for anatomopathological study.

RESULTS

A total of 27 lesions were performed with irrigated catheters (11 closed circuit and 16 opened) and 6 with standard catheters in the control group. We did not find significant differences in the lesion characteristics between the two different systems of irrigated tip catheter used, nevertheless lesions performed with the closed system were slightly greater. Th lesions produced with irrigated catheters were always superior in the control group. Transmurality in the free atrial wall is frequent with both systems. We did not see any perforation in the atrial wall.

CONCLUSIONS

We did not find significant differences in the size of the lesions produced with the two systems of irrigated catheters used. These data from an experimental model can provide useful information for atrial tachycardia radiofrequency ablation procedures in humans.

Randomized comparison of efficacy of cooled tip catheter ablation of atrial flutter: anatomic versus electrophysiological complete isthmus block

There is a subset of patients with failed ablation of the cavotricuspid isthmus (CTI) using standard catheters and with 10% of the patients having recurrences. The purpose of this study was to compare the cooled and standard ablation with regard to acute successful electrophysiological achievement of bidirectional isthmus block and the subacute anatomic characteristics of the lesions. This randomized, experimental study compares the effects of ablation on the isthmus using a cooled catheter with those of a standard ablation catheter in 16 pigs. In 12 animals, CTI block was achieved after ablation (8/8 cooled and 4/8 standard). In two animals, it was not possible to achieve complete isthmus block and two had persistent slow conduction (all four using the standard catheter). After 1 week, the animals were slaughtered. The size of the lesion was greater with the irrigated tip catheters. Transmural lesions were found in 14 animals. A complete line of anatomic isthmus block was not documented after thefirst line in six animals, four with the standard and two with the cooled catheter. A conduction block was never present across gaps > or = 5 mm. In conclusion cooled catheters achieved a complete line of electrophysiological and anatomical block in a significantly higher percentage than the standard catheters.

The effect of thiamine supplementation on tumour proliferation. A metabolic control analysis study

Thiamine deficiency frequently occurs in patients with advanced cancer and therefore thiamine supplementation is used as nutritional support. Thiamine (vitamin B1) is metabolized to thiamine pyrophosphate, the cofactor of transketolase, which is involved in ribose synthesis, necessary for cell replication. Thus, it is important to determine whether the benefits of thiamine supplementation outweigh the risks of tumor proliferation. Using oxythiamine (an irreversible inhibitor of transketolase) and metabolic control analysis (MCA) methods, we measured an in vivo tumour growth control coefficient of 0.9 for the thiamine-transketolase complex in mice with Ehrlich's ascites tumour. Thus, transketolase enzyme and thiamine clearly determine cell proliferation in the Ehrlich's ascites tumour model. This high control coefficient allows us to predict that in advanced tumours, which are commonly thiamine deficient, supplementation of thiamine could significantly increase tumour growth through transketolase activation. The effect of thiamine supplementation on tumour proliferation was demonstrated by in vivo experiments in mice with the ascites tumour. Thiamine supplementation in doses between 12.5 and 250 times the recommended dietary allowance (RDA) for mice were administered starting on day four of tumour inoculation. We observed a high stimulatory effect on tumour growth of 164% compared to controls at a thiamine dose of 25 times the RDA. This growth stimulatory effect was predicted on the basis of correction of the pre-existing level of thiamine deficiency (42%), as assayed by the cofactor/enzyme ratio. Interestingly, at very high overdoses of thiamine, approximately 2500 times the RDA, thiamine supplementation had the opposite effect and caused 10% inhibition of tumour growth. This effect was heightened, resulting in a 36% decrease, when thiamine supplementation was administered from the 7th day prior to tumour inoculation. Our results show that thiamine supplementation sufficient to correct existing thiamine deficiency stimulates tumour proliferation as predicted by MCA. The tumour inhibitory effect at high doses of thiamine is unexplained and merits further study.

Progress report on the palliative therapy of 100 patients with neoplastic effusions by intracavitary low-dose interleukin-2

OBJECTIVE

Several cytokines, particularly IL-2 and interferons, are thought to be effective in the palliative therapy of neoplastic effusions. We report on the activity and toxicity of intracavitary administration of low-dose IL-2 in a case series of 100 cancer patients with neoplastic effusions.

METHODS

One hundred patients with advanced solid tumors and neoplastic effusions underwent IL-2 intracavitary injection as first-line treatment. The most common sites of fluid accumulation were pleura (n = 68), peritoneum (n = 21) and pericardium (n = 11). Breast cancer, lung cancer and mesothelioma were the most frequent neoplasms in our series. One cycle consisted of intracavitary IL-2 at 6,000,000 IU on days 1 and 7.

RESULTS

According to Paladine's criteria, an objective clinical response was achieved in 72% (complete response in 27% and partial response in 45%), with a median duration of 5 months (range: 1-11 months). The peritoneum was the least responsive site for neoplastic effusion reduction. IL-2 intracavitary injection was well tolerated in all patients; the only toxicity observed was fever >38 degrees C in 6% of the patients.

CONCLUSION

This study shows that intracavitary injection of IL-2 represents a feasible, well-tolerated and effective therapy of neoplastic fluid accumulation. Further studies are needed in order to compare the effectiveness of intracavitary IL-2 with other standard treatments.

[Macroscopic and microscopic study of the right coronary artery after radiofrequency catheter ablation of cavotricuspid isthmus in an experimental model]

INTRODUCTION AND OBJECTIVES

The right coronary artery (RCA) is found in the AV groove, just below the ablation target of atrial flutter, the cavotricuspid isthmus (ICT). After radiofrequency (RF) ablation with standard catheters, there have been no reports of complications, but it may not be successful in 10% of the cases. However, the use of irrigated tip catheters, which create deeper lesions, might potentially damage the coronary tree.

METHODS

We analyzed the effects of ICT RF ablation on the coronary tree, with macroscopic and microscopic anatomopathological study. Ablation on ICT was performed using an irrigated tip catheter in 16 pigs and was randomly compared with a standard ablation catheter. There were no clinical problems, modifications of ST or new arrhythmias during the ablation. The heart was extracted at 1 week.

RESULTS

The macroscopic study demonstrated that the right coronary artery was preserved, along the ICT, surrounded by the epicardial fat. The microscopic study showed an inflammatory reaction in the epicardial fat that reached the adventitia of the coronary artery, but never produced necrosis in 14 cases. The muscular wall of the artery had signs of focal inflammation without endothelium involvement in 2 cases. However, we found a subepicardial vein completely damaged by the radiofrequency.

CONCLUSIONS

Although the right coronary artery is located just below the isthmus, no necrosis was observed in any case. However, there was an inflammatory reaction that focally reached the muscular wall. The veins may be damaged in RF ablation, perhaps due to the different blood flow of each vessel.

[Radiofrequency ablation of recurrent monomorphic ventricular tachycardia in a patient with severe systemic scleroderma]

A case of progressive systemic scleroderma in a 33 year-old woman who was referred to our Arrhythmia Unit due to daily palpitations and dizziness is presented. The 24-hour Holter recording showed monomorphic ventricular tachycardia which lasted several minutes. Hemodynamic study showed dilated right chambers and right ventricular dysfunction, without pulmonary hypertension. Left ventricular angiography and coronary arteries were normal. During programmed electrical stimulation, two different ventricular tachycardia were induced and ablated with radiofrequency on the right ventricle. The patient remains free of recurrence of tachycardia after (10 months of follow up). Patients with progressive systemic scleroderma may present several different cardiac arrhythmias. Involvement of the right ventricle is particularly frequent as is the origin of ventricular tachycardia in this ventricle. Radiofrequency catheter ablation is safe and effective in the management of these patients.

Lack of efficacy of atenolol for the prevention of neurally mediated syncope in a highly symptomatic population: a prospective, double-blind, randomized and placebo-controlled study

OBJECTIVES

This study was designed to evaluate the efficacy of atenolol for the long-term management of patients with vasovagal syncope. The primary hypothesis was that atenolol is not superior to placebo for the treatment of vasovagal syncope.

BACKGROUND

There is no definitive well-controlled analysis of the efficacy of beta-adrenergic blocking agents in patients with recurrent vasovagal syncope.

METHODS

This is a prospective, randomized, double-blind, placebo-controlled study. Fifty patients with recurrent vasovagal syncope were included (at least two episodes in the last year). A baseline tilt test was performed. Twenty patients (40%) had a positive tilt test. Intravenous atenolol prevented a second positive tilt in five patients. The patients were randomized to receive either atenolol or a placebo (26 patients atenolol 50 mg/day, 24 patients placebo). The follow-up procedure lasted one year. The primary end point of the study was the time to first recurrence of syncope.

RESULTS

In the intention-to-treat analysis, the group treated with atenolol had a similar number of patients with recurrent syncopal episodes as the placebo group. The Kaplan-Meier actuarial estimates of time to first syncopal recurrence showed that the probability of remaining free of syncope drops similarly in both groups and that there was no statistical difference between both curves (patients treated with atenolol vs. the placebo) with a log-rank test p value of 0.4517.

CONCLUSIONS

The recurrence of neurocardiogenic syncope in highly symptomatic patients treated with atenolol is similar to that of patients treated with placebo.